Cytokines are cell-signaling, immunomodulating, proteins that are secreted by a variety of cell types and are used extensively for intercellular communication. Almost all nucleated cells, but especially endothelial and epithelial cells and their resident macrophages, are potent producers of cytokines. Proinflammatory cytokines include interleukin-12 (“IL-12”), interleukin-11 (“IL-11”), interleukin-17 (“IL-17), interleukin-18 (“IL-18), interleukin-5 “(IL-5”), interleukin-4 (“IL-4”), interferon-gamma (“IFN-γ”), interleukin-8 (“IL-8”), tumer necrosis factor alpha (“TNF-α”), tumer necrosis factor beta (“TNF-β”), interleukin 6 (“IL-6”), interleukin-1 (“IL-1”), interleukin-20 (“IL-20”), interleukin-33 (“IL-33”), leukocyte inhibitory factor (“LIF”), oncostatin M (“OSM”), ciliary neurotrophic factor (“CNTF”), transforming growth factor-beta (“TGF-β”), granulocyte-macrophage colony (“GM-CSF”). In particular, IL-17 is a cytokine that acts as a mediator in delayed-type reactions by increasing chemokine production in various tissues to recruit monocytes and neutrophils to the site of inflammation. IL-17 is produced by T-helper cells and is induced by IL-23, which results in destructive tissue damages in delayed-type reactions. IL-17 functions as a proinflammatory cytokine that responds to the invasion of the immune system by extracellular pathogens and induces destruction of the pathogen's cellular matrix.
Immune regulatory functions have been reported for the IL-17 family of cytokines, perhaps due to the fact that IL-17 cytokines induce many immune signaling molecules. IL-17 is involved in inducing and mediating proinflammatory responses. Additionally, IL-17 is associated with allergic responses, as it induces the production of many other cytokines including, but not limited to, IL-6, B-CSF, GM-CSF, IL-1β, TGF-β, TNF-α, chemokines, including IL-8, GRO-α, and MCP-1, and prostaglandins, such as PGE2. IL-17 includes the production of these proinflammatory compounds in a variety of cell types including fibroblasts, endothelial cells, epithelial cells, keratinocytes, and macrophages.
Due to its ability to induce the inflammatory response, IL-17 has been linked to many immune and autoimmune related diseases. Inflammatory conditions mediated by IL-17 include asthma, allergies, skin conditions such as dermatitis, psoriasis and eczema, inflammatory bowel disease, and arthritis. Traditional medications used to treat autoimmune diseases attempt to stop the inflammation involved in the autoimmune attack. However, many of these medications also suppress the ability of the immune system to fight infection and have, potentially, many serious side effects. Furthermore, the inflammatory response plays a significant role in the onset of certain neonatal and childhood diseases.
Accordingly, there is a need for safe, yet effective, nutritional compositions that reduce the inflammatory response in a subject. More particularly, there is a need for infant formulas that reduce the inflammatory response in an infant, and thereby help reduce the onset of certain neonatal and childhood diseases without substantially altering the ability of the immune system to fight infection, and do not produce unwanted side effects when consumed.